Studies on the inhibition of lymphocyte transformations by polyene fatty acid complexes of alphafetoprotein (AFP) and of serum albumin are being continued using mouse, rat and human sources of protein. AFP appears to bind polyene fatty acids that have been covalently complexed through their carboxyl groups with daunomycin. These complexes have been found to inhibit some animal tumors which produce AFP and will be extended to studies of other AFP-producing tumors. Isotypic antibodies to human lambda-type L-chains can be used to detect Bence Jones proteins of similar serological specificity which contain variable region sequence segments which are identical or quite similar. Analogous studies will be carried out with K-chains. Results of these studies may provide an eventual background to determine how identical DNA sequences giving rise to definitive L-chain variable region segments are incorporated into genes controlling the synthesis of residues 1 to 95 of their variable regions. Collaborative studies of the relationships of amino acid sequences of human L-chains to their X-ray crystallographic structures are being continued. The protein ubiquitin isolated from mature erythrocytes has been found to possess weak CO2 hydration and esterase activities. In the latter reaction with specific acetate esters the protein appears to become acetylated. The extent and location of these acetyl groups in this 76-residue protein will be determined as well as the possible transferance of these groups to other proteins.